Carbene complexes from the reaction of ionic isocyanide complexes of gold(I) with alcohols and amines

Abstract

The synthesis and properties of several new types of carbene complexes obtained by reaction of the ionic gold(I) isocyanide complexes, [(RNC) 2Au] +, (R = p-CH 3C 6H 4, C 6H 11) with alcohols ROH (R = CH 3, C 2H 5) and amines RR′NH (R = H; R′ = p-FC 6H 4, p-CH 3C 6H 4, C 6H 5CH 2, CH 3, C 6H 11, o,o′-[(CH 3) 2C 6H 3; R = CH 3, R′ = C 6H 5), are described. Both bis-carbene [(carbene) 2Au] + and monocarbene [(carbene)(RNC)Au] + complexes can be obtained according to the nature of the parent complex and of the nucleophilic agent. As evidenced by their NMR spectra, the bis-carbene complexes are obtained as a mixture of geometrical isomers which in the case of [{( p-CH 3C 6H 4NH)(C 2H 5O)C} 2Au]ClO 4 were separated by fractional crystallization. The carbene ligand can be easily displaced with triphenylphophine yielding the mixed complexes [(carbene)(PPh 3)Au] +; in the case of a diaminocarbene the displaced ligand rearranges to give the corresponding formamidine, HC(NR)NHR.